The present invention relates to a novel Staphylococcus aureus antigen, and to a method for obtaining and using the antigen.
S. aureus causes several diseases in animals and in humans by various pathogenic mechanisms. The most frequent and serious of these diseases are bacteremia and its complications in hospitalized patients. In particular, S. aureus can cause wound infections and infections associated with catheters and prosthetic devices. Serious infections associated with S. aureus bacteremia include osteomyelitis, invasive endocarditis and septicemia. The problem is compounded by multiple antibiotic resistance in hospital strains, which severely limits the choice of therapy. In addition, S. aureus is a major cause of mastitis in dairy and beef cattle, where the infection causes a major loss of income.
A S. aureus vaccine would provide a solution for the problem of antibiotic resistance. At least eight different serotypes of S. aureus have been identified using polyclonal and monoclonal antibodies to capsular polysaccharide (CPS). Karakawa et al., J. Clin. Microbiol. 22:445 (1985). The contents of this document and all others listed herein are incorporated herein by reference.
Surveys have shown that approximately 85-90% of human clinical isolates, and a comparable, although somewhat lower percentage of animal clinical isolates, are capsular polysaccharide Type 5 or Type 8. An individual vaccinated with a vaccine containing Type 5 and Type 8 CPS antigens would be protected from infection by 85-90% of clinically-significant S. aureus strains, but a significant risk of infection still would exist. A vaccine containing antigens from the other six serotypes theoretically could provide 100% protection, but would require production and purification of six additional components. This would be untenable from a practical standpoint. On the other hand, an antigen common to the isolates not typeable as Type 5 or Type 8 would enable production of a vaccine containing only three antigens.